[Studies on Hepatocystis sp. in rhesus monkeys from Yunnan, China]

A survey for the prevalence of Hepatocystis sp. was done on 10 rhesus monkeys (M. mulatta) from Yunnan, China. Examinations were performed on blood smears to detect erythrocytic gametocytes of the parasite, and on livers to detect merocysts. In 6 out of 10 monkeys, Hepatocystis sp. infection was confirmed. The gametocytes took about 6 days to reach maturity. The fully grown macrogametocytes were about 8 microns in diameter. The cytoplasm was stained pale lilac and the nucleus consisted of dense chromatin dots lying in an unstained zone. The microgametocytes had cytoplasm dyed a biscuit color and large nuclei dyed pink. In the pathological section of livers, the merocyst measured about 3 mm in diameter and had a smooth outline without any projecting limb. The characteristics of this protozoan species were very similar to those of H. taiwanensis. However, more work should be done to clarify the relationship between this species and H. taiwanensis.